Machine-readable optical security device

ABSTRACT

An IR and/or UV machine-readable optical security device (e.g., micro-optic security thread) that is made up of at least one IR-absorbing component with a characteristic IR signature detectable at two or more IR-wavelengths, at least one UV-absorbing component with a characteristic UV signature detectable at two or more UV-wavelengths, at least one IR-absorbing component that absorbs IR light and emits light at a different invisible wavelength, at least one UV-absorbing component that absorbs UV light and emits light at a different invisible wavelength, or a combination thereof, is provided. The IR and UV machine-readable features do not interfere with the optical effects projected by the optical material.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of U.S. application Ser. No.17/304,446, filed Jun. 21, 2021, which is a continuation of U.S.application Ser. No. 15/868,530, filed Jan. 11, 2018, which claimspriority under 35 U.S.C. § 119(e) to U.S. Provisional Patent ApplicationNo. 62/457,226, filed Feb. 10, 2017, the disclosures of which areincorporated herein by reference.

TECHNICAL FIELD

The present invention generally relates to a machine-readable opticalsecurity device (MrOSD) that is suitable for use in securing (i.e.,authenticating and/or aestheticizing) high security products such ashigh value articles of manufacture or high value documents. The MrOSDincludes an optical security device (OSD) coupled to a Mr-componenthaving a characteristic machine readable signature (Mr-signature) suchas an infrared (IR) and/or ultraviolet (UV) signature, which may also bevisible in reflection or in transmission. The Mr-component imparts acharacteristic Mr-signature to the OSD such that the OSD, when coupledalong with the Mr-component to a high security product, is identifiableby a signature detector. As such, when the MrOSD is coupled to a highsecurity product, such as a banknote, the signature detector can therebyidentify the presence/absence of the OSD and thereby authenticate thehigh security product. The OSD is a transparent/translucent micro-opticsecurity device through which the signature of the Mr-component can beread by the signature detector.

BACKGROUND

Optical materials are often employed to authenticate banknotes and otherhigh security products and to provide visual enhancement of manufacturedarticles and packaging. Such materials have evolved mainly from a driveto resist counterfeiting of certain high value documents or high valuearticles and/or to render such counterfeiting attempts obvious. Examplesof optical materials used in anti-counterfeiting applications includeimage systems that rely on arrays of lenticular or cylindricalstructures or arrays of microlenses to project images that exhibit oneor more mobile effects when the optical materials are viewed fromvarying points of view. Because of these mobile effects, the projectedimages cannot be effectively reproduced using traditional orcontemporary printing and/or photocopying processes.

Optical materials based upon the concept of moiré magnification havebeen and are currently used in anti-counterfeiting applications. Suchmaterials are typically multi-layered materials that include a lenslayer containing an array of lenses, an intermediate spacer layer, andan image layer, which contains an array of image elements (i.e., imageicons). The lens layer may be located above or below the image layer(i.e., refractive or reflective optical materials, respectively). Theimage icons are magnified or otherwise optically altered when viewedthrough the lenses. Alternative optical materials do not include anoptical spacer.

For refractive optical materials, an upper lens layer and a image layerare configured such that when the icons are viewed through the upperlens layer one or more images are projected. These projected images mayshow a number of different mobile effects when the optical material isviewed from varying points of view (i.e., upon tilting of the opticalmaterial).

Multi-layered constructions of optical materials conforming to the abovedescriptions, which are capable of presenting such effects are describedin: U.S. Pat. No. 7,333,268 to Steenblik et al.; U.S. Pat. No. 7,468,842to Steenblik et al.; U.S. Pat. No. 7,738,175 to Steenblik et al.; U.S.Pat. No. 7,830,627 to Commander et al.; U.S. Pat. No. 8,149,511 to Kauleet al.; U.S. Pat. No. 8,878,844 to Kaule et al.; U.S. Pat. No. 8,786,521to Kaule et al.; European Patent No. 2162294 to Kaule et al.; EuropeanPatent No. EP2164713 to Kaule et al.; U.S. Pat. No. 8,867,134 toSteenblik et al.; and U.S. Pat. No. 10,890,692 to Jordan et al.

Optical materials based upon the concept of moiré magnification may alsoconstitute a single layer system such as those described in U.S. patentapplication Ser. Nos. 15/215,952 and 15/216,286 to Gregory R. Jordan,both filed Jul. 21, 2016, and in U.S. patent application Ser. No.14/975,048 to Cape et al., filed Dec. 18, 2015.

These single layer systems can comprise a surface and a periodic arrayof image relief microstructures having a periodic surface curvaturedisposed on or within the surface. The image relief microstructures canhave a first image repeat period along a first image reference axiswithin the array, and the periodic surface curvature can have a firstcurvature repeat period along a first curvature reference axis withinthe array. Transmission of light through the array, reflection of lightfrom the array, or a combination thereof forms a magnified moiré image.

The image relief microstructures can be (+)-relief or (−)-relief imagerelief microstructures. In some cases, the image relief microstructurescan be (+)-relief image relief microstructures that upwardly projectfrom the surface terminating in an arcuate image generating surface. Inother cases, the image relief microstructures can be (−)-relief imagerelief microstructures that are voids formed within the surfaceterminating in an arcuate image generating surface. Depending on thedesired appearance of the magnified moiré image, the image reliefmicrostructures can be a positive image representation or a negativeimage representation.

The above-described optical materials can be utilized in a variety ofdifferent forms (e.g., strips, patches, security threads, planchettes)with any product and in particular with any security product (e.g., highsecurity products or high value products) such as banknotes, checks,stamps, government letterheads, stock certificates, lottery tickets,other secure documents and other high value or secure commercialproducts, apparel, identification, passports and other government issueddocuments, product packaging, or the like, for authentication oraestheticizing purposes. For banknotes and secure documents, thesematerials are typically used in the form of a strip, patch, or threadand can be fully or partially embedded within the banknote or document,or applied to a surface thereof. For passports or other identification(ID) documents, these materials could be used as a full laminate orinlayed in a surface thereof. For product packaging, these materials aretypically used in the form of a label, seal, or tape and are applied toa surface thereof.

It has long been recognized that the use of machine testable securityfeatures with security devices used on or within a security document orarticle offer a heightened level of security. In fact, many securityproducts, such as secured documents, include a security device (e.g.,security thread) that is disposed on or within the paper, includes oneor more machine detectable/readable (Mr-) security features, such asmagnetic features that serve to authenticate the security paper andprevent or deter counterfeiting. For example, in GB 2,227,451 B, asecurity device in the form of a security thread comprises a plasticstrip. Along a surface of the plastic strip is a coating of metal and amachine readable, discontinuous track of magnetic material, which isdivided into machine-readable word and termination segments.

The above-described optical materials, however, are incompatible withconventional magnetics. Magnetic materials have a degree of inherentcolor, which renders them visually detectable in reflected andtransmitted light and thus interfere with the projected optical imagesand their corresponding mobile effects. This is particularly true wherethe magnetic color is different from the pigments used in certainmicro-optic materials as contrasting materials. Moreover, otherconventional security threads, patches or stripes include materials thatobstruct their machine readability. For example, many of these securitydevices are opaque or include certain materials, such as metals ordemetalized areas that interfere with the machine readability of themachine readable components. For these reasons, heretofore it has beenimpractical to incorporate certain machine readable features intosecurity devices for high value documents or high value articles.

A need therefore exists for an optical material, such as a micro-opticsecurity device, that employs a machine detectable and/or readablefeature that does not interfere with the optical effects projected bythe optical material and where the optical security device does notinterfere with the machine-readable signature.

SUMMARY

The present invention provides such a machine-readable optical securitydevice (MrOSD) by avoiding at least one of the above impediments toincorporating a machine readable component into an optical securitydevice. In a particular aspect the present invention provides an MrOSD.In one embodiment of this aspect, the MrOSD comprises an OSD component;and an Mr-component coupled to the OSD and imparting a characteristicmachine-readable Mr-signature to the OSD; wherein the Mr-signaturedisplays at least one machine readable Mr-signal within the invisiblespectral range; wherein the OSD is transparent or translucent; andwherein the Mr-signature is readable, through the OSD, by a signaturedetector. In another embodiment, the MrOSD is an IR and/or UVmachine-readable optical security device (e.g., micro-optic securitythread) that comprises at least one of (i) a first IR-component having acharacteristic signature (e.g., IR signature) that is detectable at twoor more wavelengths (i.e., IR-wavelengths), (ii) a first UV-componenthaving a characteristic signature (e.g., UV signature) detectable at twoor more wavelengths (e.g., UV-wavelengths), (iii) a second IR-componentthat absorbs IR light and emits light at a different invisiblewavelength, and (iv) a second UV-component that absorbs UV light andemits light at a different invisible wavelength.

In another aspect, the present invention provides a method of making anMrOSD. In one particular embodiment of this aspect, this methodcomprises (i) forming an OSD where the OSD at least comprises (a) afocusing layer of focusing elements, (b) an image layer of imageelements disposed relative to the focusing layer such that a syntheticimage is projected by the OSD when the image elements are viewed throughthe focusing elements; and optionally (c) at least one additional layercoupled to at least one of the focusing layer or the image layer and(ii) coupling an Mr-component to the OSD such that the Mr-componentimparts a characteristic machine-readable Mr-signature to the OSD; wherethe Mr-signature displays at least one machine readable Mr-signal withinthe invisible spectral range; wherein the OSD is transparent ortranslucent; and wherein the Mr-signature is readable, through the OSD,by a signature detector. In another particular embodiment of aspect,this method comprises (i) forming an OSD where the OSD at leastcomprises (a) a focusing layer of focusing elements, (b) an image layerof image elements disposed relative to the focusing layer such that asynthetic image is projected by the OSD when the image elements areviewed through the focusing elements; and optionally (c) at least oneadditional layer coupled to at least one of the focusing layer or theimage layer and (ii) introducing (e.g., coupling) at least oneMr-component to the OSD. For this method, the Mr-component is asdescribed above.

In another aspect, the present invention provides a secured product. Inone particular embodiment, the secured product comprises an MrOSD, asdescribed herein, wherein the MrOSD is coupled to a substrate of a highsecurity product. In another aspect, the present invention provides ause for the MrOSD. In one particular embodiment, this use comprisesusing the MrOSD to secure a high security product, wherein the MrOSD isas described herein throughout.

In another aspect, the present invention provides a sheet material and abase platform that are made from or employ the inventive MrOSD, as wellas documents made from these materials.

In a particular embodiment of the aspects of the invention presentedabove, the optical security device of the present invention is amicro-optic security device (MOSD), such as a security thread, thatcomprises an IR-component with an IR signature that is detectable at twoIR-wavelengths, where the ratio of absorption between the twoIR-wavelengths is reliably and measurably the same when measured intransmission.

In another exemplary embodiment, the OSD of the MrOSD is a micro-opticsecurity device (e.g., security thread) that comprises an IR-absorbingcomponent that absorbs IR light and emits light at a different invisiblewavelength and/or a UV-absorbing component that absorbs UV light andemits light at a different invisible wavelength (e.g., IR and/or UVphosphors). The emitted light may be viewed from the same side as theincident light or from an opposite side of the device.

In view of the present disclosure, various other aspects, embodiments,features and advantages of the invention will, in hindsight, be apparentto a person having ordinary skills in the art (PHOSITA).

BRIEF DESCRIPTION OF THE DRAWINGS

Particular features of the disclosed invention are illustrated byreference to the accompanying drawings in which:

FIGS. 1 a-f are top side images of exemplary embodiments of paperdocuments employing different optically variable security threadsaccording to the present invention, as viewed in IR transmission, wherethe IR-absorbing component of the inventive optically variable securitythreads is present in the form of intermittent patterns, namely, similaror different size horizontal bars (FIGS. 1 a, 1 d, 1 e ), chevrons orzig zags (FIG. 1 c ), angled bars (FIG. 1B), and indicia (FIG. 1 f ).

FIG. 2 is a cross-sectional view of a machine readable optical securitydevice with the Mr-component within the image layer.

FIG. 3 is a cross-sectional view of a machine readable optical securitydevice with the Mr-component as a discrete layer.

FIG. 4 is cross-sectional view of a machine readable optical securitydevice with the Mr-component integrated as a pattern or indicia.

FIG. 5 is a cross-sectional view of a machine readable optical securitydevice with the Mr-component randomly distributed throughout a layer ofthe OSD.

FIG. 6 is an isometric view of a machine readable optical securitydevice with the Mr-component integrated with the ODS as a separate layerbetween the image layer and focusing layer.

FIG. 7 is a plan view of a secured product presented as a banknote witha windowed thread displaying the synthetic image of the MrOSD being usedto authenticate the banknote.

FIG. 8 is a graphical view of a predetermined Mr-signature withMr-signals suitable for use in detecting the authenticity of securedproduct.

DETAILED DESCRIPTION

The term “characteristic signature”, as used herein is intended to meana unique absorption or transmission (absorption/transmission) pattern,such as that depicted on a spectrogram of a material that is exposed toelectromagnetic radiation like IR or UV. This unique pattern may includeunique slopes, peaks along a wavelength/frequency scale correlating toparticular spectral absorption/transmission curves, or otherpredetermined identifying spectral characteristics such as the width oftwo or more absorption/transmission peaks, the height to widthrelationship of two or more peaks, the ratio of absorption/transmission(height) between two absorption/transmission peaks, or changes in thecurvature of the spectrum. These can include absorption/transmissionmaxima (peaks) and/or absorption/transmission minima and/orabsorption/transmission edges at substantially the same wavelengths.

The term “coupling” or “couple”, as used herein, is intended to meanthat the component is either directly or indirectly secured to anothercomponent.

The term “detectable”, as used herein, is intended to mean reliablymeasurable IR and/or UV absorbance (or transmittance) at two or morewavelengths using a detector that reacts to IR and/or UV radiation, whenthe inventive optical security device is present on or partially withina paper or polymer sheet material.

The term “imparting”, as used herein, is to be understood as adding toor enabling the OSD to be authenticated/identified, or its presence orabsence to be determined, by the presence or absence of theMr-signature.

The term “integrated”, as used herein, refers to the incorporation ofthe Mr-component into a layer or array of the OSD by, for example,having the Mr-component distributed in the formulation used to preparethe OSD layer.

The term “intermittent pattern”, as used herein, is intended to meanthat when viewed (by machine or with a viewer that images at theappropriate wavelength) in IR or UV illumination, an optionallyrepeating pattern (e.g., an encoded pattern) may be seen on themicro-optic security device.

The term “integration” or “integrating”, as used herein, is intended tomean that the subject component is added to at least a bulk portion ofanother component of the invention.

The term “introducing”, as used herein, is intended to mean that thesubject component is added to another component of the invention byintegration or layering.

The term “layering”, as used herein, is intended to mean that thesubject component is coupled to another component in a continuous ordiscontinuous layer under or over another referenced component/layer ofthe invention such that at least one surface of each component issubstantially parallel to a surface of the other component/layer.

The term “spectral range”, as used herein refers to the relative rangesof wavelengths among the electromagnetic range including, for example,the UV-spectral range, the IR-spectral range, the visible-spectralrange, the x-ray-spectral range, etc.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by a PHOSITA. Allpublications, patent applications, patents and other referencesmentioned herein are incorporated by reference in their entirety. Incase of conflict, the present specification, including definitions, willcontrol. In addition, the materials, methods, and examples areillustrative only and are not intended to be limiting.

As noted above, the present invention may be described in severalaspects, including an MrOSD, methods of manufacturing an MrOSD, asecured product comprising an MrOSD, use of an MrOSD in securing certainsecurity products and certain sheet materials, base platforms ordocuments made from an MrOSD. Particularly, the MrOSD, forming elementsof these aspects of the invention, comprises an OSD and an Mr-componentthat is coupled to the OSD.

The optical security device (OSD) of the present invention is either (a)a multi-layered material or (b) a single-layered material. Exemplarymulti-layered materials include those having one or more focusingelement layers coupled to one or more image layers. At least one of thefocusing element layers includes an array of focusing elements while atleast one of the image layers includes an array of image elements. Thefocusing element layer having the array of focusing elements is layeredwith the image layer having the array of image elements such that whenthe image elements are viewed through the focusing elements, from atleast one point of view, a synthetic image is projected by the OSD. Itis contemplated within the scope of the present invention that themulti-layered material, in certain embodiments, includes additionallayers or arrays. For example, in one such embodiment, the OSD furtherincludes an optical spacer layer that is disposed between the imagelayer and the focusing element layer. Alternatively, where the OSD is asingle-layered material, the single-layered construction is made up of asubstrate with a surface having a periodic array of image reliefmicrostructures and a periodic surface curvature disposed on or withinthe surface, which forms a magnified moiré image.

In hindsight from the present disclosure, various suitable OSDs willbecome apparent to a PHOSITA. For example, certain suitable OSDs are asdescribed in U.S. Pat. No. 7,333,268 to Steenblik et al., U.S. Pat. No.7,468,842 to Steenblik et al., and U.S. Pat. No. 7,738,175 to Steenbliket al. and these OSDs include focusing element layers formed from avariety of formulation materials such as substantially transparent orclear, colored or colorless polymers such as acrylics, acrylatedpolyesters, acrylated urethanes, epoxies, polycarbonates,polypropylenes, polyesters, urethanes, and the like, using amultiplicity of methods that are known in the art of micro-optic andmicrostructure replication, including extrusion (e.g., extrusionembossing, soft embossing), radiation cured casting, and injectionmolding, reaction injection molding, and reaction casting. Highrefractive index, colored or colorless materials having refractiveindices (at 589 nm, 20° C.) of more than 1.5, 1.6, 1.7, or higher, suchas those described in U.S. Patent Application Publication No. US2010/0109317 A1 to Hoffmuller et al., may also be used in the practiceof the present invention. Materials and methods for providing the imagelayer, spacer layer and additional layers are likewise suitablydisclosed in the above incorporated patent documents.

Though various methods of manufacturing the OSD will be apparent in viewof the present disclosure, an exemplary method of manufacturing themulti-layered construction comprises forming the image layer by formingan array of image elements, in a radiation cured liquid polymer (e.g.,acrylated urethane) that is cast against a base film (i.e., an opticalspacer), such as 75 gauge adhesion-promoted polyethylene terephthalate(PET) film; forming the focusing element layer by forming an array offocusing elements in a radiation cured polymer disposed on the oppositeface of the base film. Suitable image elements and methods of providingthem are described in International Patent Application Publication Nos.WO/2005/052650, WO/2006/125224, WO/2008/008635, WO/2011/019912,WO/2011/163298, WO/2013/028534, WO/2014/143980, WO/2009/017824,WO/2016/044372, WO/2016/011249, WO/2013/163287, WO/2007/133613,WO/2012/103441, WO/2015/148878, WO/2005/106601, and WO2006/087138, whichare all incorporated herein in their entirety. In preferred embodiments,the image elements are in the form of voids, solid regions, protrusions,or any combination thereof. Suitable focusing elements and methods ofproviding them are described in International Patent ApplicationPublication Nos. WO/2005/052650, WO/2006/125224, WO/2008/008635,WO/2011/019912, WO/2011/163298, WO/2013/028534, WO/2014/143980,WO/2009/017824, WO/2016/044372, WO/2016/011249, WO/2013/163287,WO/2007/133613, WO/2012/103441, WO/2015/148878, WO/2017/105504,WO/2005/106601, and WO/2006/087138, which are all incorporated herein intheir entirety. In preferred embodiments, the focusing elements aremicrolenses. The array of focusing elements and the array of imageelements are disposed on opposing sides of the base film and areoriented (array alignment or skew) relative to each other such that whenthe image elements are viewed through the focusing elements a desiredsynthetic image is projected. Preferably, the image elements are coupledwith a contrasting material thereby enhancing the optical effect of thesynthetic image. For example, the contrasting material may be coupled tothe image elements by coating (e.g., full, partial, or patterned) thefront or back of the voids and/or solid regions, by filling the voids,or by coating (e.g., full, partial or patterned) the protrusions. In apreferred embodiment, the image elements are voids that are filled, orsubstantially filled, with a contrasting material, thereby providingimproved contrast between the images projected from the void areas andthe surrounding solid regions. Various suitable contrasting materialswill be apparent in view of the present disclosure, however Applicanthas found it most suitable to use an ink, dye or pigment with sub-micronparticle/pigment size. Applying the contrasting material to the imageelements may be by gravure-like doctor blading against the film surface,followed by solidifying the filling of contrasting material by suitablemeans (e.g., solvent removal, radiation curing, or chemical reaction).

Materials, formulations and methods of manufacturing the above-mentionedsingle-layered construction of the OSD are described in U.S. patentapplication Ser. Nos. 15/215,952 and 15/216,286, both filed Jul. 21,2016, and in U.S. patent application Ser. No. 14/975,048, filed Dec. 18,2015.

The optical security device of the present invention may furthercomprise additional features and layers, such as those described in U.S.Pat. No. 7,333,268 to Steenblik et al., U.S. Pat. No. 7,468,842 toSteenblik et al., and U.S. Pat. No. 7,738,175 to Steenblik et al. Forexample, the inventive device may further comprise additional layers(e.g., embedding, sealing or obscuring layers), textured surfaces forbetter adhesion to further layers, adhesion promoters, etc.

In one such embodiment, the inventive optical security deviceadvantageously contains an obscuring layer on the side of the OSDproximate the image layer of the multi-layer material, or on thebackside of the single-layer material, the obscuring layer serving toconceal the device when viewed from the underside of a host sheetmaterial (e.g., a banknote).

The OSD of the present invention is preferably transparent ortranslucent such that the Mr-component can be readily and/or reliablyread by the signature detector through the OSD without the Mr-componentinterfering (i.e., reducing image resolution, distorting, or blocking)with the synthetic image. As such the layers of the OSD, whether inmulti-layered or single-layered construction, must allow suchtransparency or translucency.

As noted, the MrOSD includes an Mr-component. Various suitableMr-components will become apparent to a PHOSITA in hindsight of thepresent disclosure. The Mr-component is coupled with the OSD byintegrating one or more of such Mr-components into one or more layers ofthe inventive MrOSD, or the Mr-component(s) is coupled with the OSD byapplying a discrete layer(s) (e.g., Mr-layer) by, for example, coatingthe Mr-component onto a layer, or between layers, of the OSD or byseparately forming an Mr-component layer (e.g., Mr-layer) andsubsequently coupling that Mr-layer to the OSD. The Mr-component can beintegrated as a mixture, dispersion, solution, emulsion or the like intoa layer of the OSD. Other alternative means of integrating theMr-component with the OSD layer(s) will be apparent, in view of thepresent disclosure. A discrete layer as used herein is to be understoodas a layer that is bordered by a defined interface separating/connectingthe OSD layer from/to the Mr-component. Preferably, the Mr-component isa separate layer(s) that is applied or added to the OSD. TheMr-component, whether integrated or discrete, may be present in acontinuous fashion (i.e., a solid block) or may be in the form of anintermittent pattern or random distribution. Patterns incorporatedherein may provide aesthetics or may provide a unique readablesignature. In one embodiment, the pattern is in the form of at least oneof horizontal bars, chevrons or zig zags, angled bars, shapes, indicia,or the like, or combinations thereof, and may be visible in reflection,or more likely in transmission at the prescribed wavelengths.Preferably, the pattern is arranged to provide a distinct andrecognizable signal when read by a machine. In a particular embodiment,the pattern is a set of equally sized blocks, a set of variable sizedblocks, or a set of text.

It is generally contemplated herein that the Mr-component is an inkvehicle and can be incorporated in the various embodiments describedherein. Such ink vehicles can be transparent, or pigmented. In oneparticular embodiment, the MrOSD comprises an OSD coupled to theMr-component and where the Mr-component is at least one of anIR-absorbing IR-component and a UV-absorbing UV-component(s). In afurther particular embodiment, this Mr-component is in the form of anink vehicle, and is coupled to the OSD by being mixed in with aformulation used to make an opacifying layer of the OSD. While notalways the case it is contemplated herein that the quantity of theMr-components may be varied, in this particular embodiment, theIR-absorbing or UV-absorbing Mr-component(s) is present in the inkvehicle in a quantity ranging from about 30 to about 70% by wt. Aquantity of the ink vehicle ranging from about 30 to about 70% by wt. isadded to the formulation used to make the opacifying layer. Thethickness of the opacifying layer, in this exemplary embodiment, rangesfrom about 0.5 to about 5 microns.

In another exemplary embodiment, the Mr-component(s) is applied betweenthe image layer and the opacifying layer of the inventive opticalsecurity device.

In yet another exemplary embodiment, the Mr-component(s), in the form ofa coating composition, is used to form a layer directly or indirectly onthe image layer, which serves to replace the opacifying layer or whichconstitutes an additional layer(s). A pattern can be formed through thecoating process by use of a mask allowing selected intermittent areas tobe coated. If applied as a separate layer, the coating composition maybe applied between two opacifying layers. The resulting layer may be atleast as thick as each opacifying layer.

The various Mr-components are detectable by various means known orapparent to a PHOSITA including various known IR-machines, UV-machinesand the like. As noted, the Mr-component may be selected from (i) afirst IR-component imparting an Mr-signature to the OSD which includesat least two Mr-signals, that are detectable, at 2 or more wavelengthswithin the IR spectral range, (ii) a first UV-component imparting anMr-signature to the OSD which includes at least two Mr-signals, that aredetectable, at 2 or more wavelengths within the UV spectral range, (iii)a second IR-component that absorbs IR-light of a first wavelength andemits light at a second different wavelength, and (iv) a secondUV-component that absorbs UV-light and emits light at a second adifferent wavelength. The Mr-signature is a predetermined characteristicset of Mr-signals. These characteristic set of Mr-signals can bedetected by, for example, a spectrometer that provides a graphicaldisplay of the Mr-signals. These Mr-signals may be plotted on a graphhaving an x-axis of wavelengths and a y-axis of % transmittance or %absorption over a range of wavelengths and a range of %transmittance/absorption. As such the Mr-signature may include variousMr-signals (peaks, valleys, area under curve, distance between peaks orvalleys, slope between particular peaks or valleys, etc.). As noted, thesecond IR-component absorbs light within the IR-spectral range and emitslight at a second and different wavelength. In a preferred embodiment,the second and different wavelength is within a separate invisiblespectral range. However, it is also contemplated herein that the secondand different wavelength is either in the visible spectral range or iswithin the same spectral range as the absorption. This is likewise forthe second UV-component.

In one embodiment, the MrOSD comprises an OSD component coupled to anMr-component, as described herein, where the Mr-component is anIR-absorbing IR-component. This IR-component is presented as an inkvehicle having an IR-taggant distributed therein that is detectable at apredetermined wavelength (or set of wavelengths) within the IR-spectralrange. Alternatively, the Mr-component is a UV-absorbing UV-component,where said UV-component is presented as an ink vehicle having aUV-taggant distributed therein, that is detectable at a predeterminedwavelength (or set of wavelengths) within the UV-spectral range.

Various suitable Mr-components are selected based on the desiredpredetermined wavelengths at which the Mr-signals are desired.Accordingly, various predetermined wavelengths are contemplated. Forexample, in certain embodiments where the MrOSD includes a firstIR-component and/or a first UV-component, each are independentlydetectable at 2 or more wavelengths and in a particular embodiment, theIR-component is detectable within a spectral range from about 750 nm toabout 850 nm (preferably about 800 nm) (with about 70-80% absorption;preferably 75%) and about 850 nm to about 950 nm (preferably 870 nm-890nm) (with about 75-80% absorption; preferably about 77-78% absorption)while the UV-component, if present, is detectable at about 10 nm toabout 400 nm (preferably about 200-300 nm; preferably 275 nm) (withabout 70-80% absorption; preferably 75% absorption) and about 300-400 nm(preferably 350 nm) (with about 75-85% absorption; preferably 80%absorption). In one exemplary embodiment, the Mr-component includes anIR-absorbing component where this component is detectable, by anIR-machine, only in the infrared region of the electromagnetic spectrumor it may be detectable in the infrared region and observable (andpossibly also machine detectable) in the visible regions of thespectrum. In a preferred embodiment, the IR-absorbing component isdetectable in the near-infrared (NIR) region of the electromagneticspectrum.

The Mr-component in one embodiment is selected from the group ofsuitable IR-taggants and the group of IR-detectable pigments formingpart of an ink vehicle. Suitable pigments and taggants are described inU.S. Pat. No. 6,926,764, which is incorporated herein in its entirety.Accordingly, the ink vehicle can be an ink set comprising a first set ofink including an IR-taggant with a first Mr-signal, and a black, yellowor magenta dye; and a second set of ink including a pigment with asecond Mr-signal; wherein the first Mr-signal and the second Mr-signalare substantially the same; and wherein the ink set includes at leasttwo inks of different colors. Preferably the second ink set include cyanhaving a pigment which provides a Mr-signature with at least oneMr-signal that is substantially the same as at least one Mr-signalprovided by the IR-taggant. As such, the substantially the sameMr-signals are within 10 nm of each other. Particularly, in a preferredembodiment, the IR-taggant is a phthalocyanine and preferred pigmentsare crystallographic X-forms of phthalocyanine. In more preferredembodiments, the IR-taggant is at least one of a substitutedphthalocyanine, a naphthalocyanine, a metal-containing phthalocyanine ora poly-substituted phthalocyanine or combinations thereof.Benzenethiol-substituted copper-phthalocyanines are preferredIR-taggants; more preferably para-toluenethiol-persubstitutedcopper-phthalocyanine of the formula:

In one such embodiment, the IR-absorbing component is an IR-reactivepigment sold as part of an ink or ink vehicle under the tradedesignation SICPATalk by SICPA SA, Av de Florissant 41, 1008 Prilly,Switzerland. The pigment may be an organometallic pigment such as ametal-containing phthalocyanine pigment which absorbs or reflects morethan 75% of any near IR light when viewed in transmission (% T<25% from750-950 nm), and which is viewable at the following wavelengths: 750 nm;and 900 nm. The ratio of absorption between the two IR-wavelengths isequal to about 35 percentage points. This pigment has an off-white bodycolor in the visible region of the electromagnetic spectrum.

Suitable IR-absorbing components are described in GB 2,168,372, wherecertain IR- or UV-absorbing materials that are invisible or transparentin the visible region are disclosed, and in WO 90/1604 where certainIR-taggants are described, which exhibit narrow absorptioncharacteristics; those including rare earth compounds. Other suitableIR-absorbing components are described in EP 553614 where certainphthalocyanines are used as a printing ink and provide spectralabsorption in the wavelength range of 700 to about 1200 nm. EP 484018describes suitable phthalocyanines having absorption wavelengths maximumbetween about 680 and 900 nm. EP 408191 describes substitutedphthalocyanines with characteristic wavelength absorptions in the rangeof 700 to 1500 nm that are also suitable in the present invention.Naphthalocyanine compounds are also suitable and are described furtherin EP134518 as IR-absorbers the absorbing near IR (NIR) radiation in thespectral range of 750 to 900 nm, which may be used as dyes or pigments.

In another such embodiment, the IR-absorbing component is an IR-reactivepigment sold as part of an ink or ink vehicle under the tradedesignation LUMOGEN-S by BASF Corporation, 100 Park Ave., Florham Park,N.J. 07932. This pigment is invisible in the visible region of theelectromagnetic spectrum.

The ink or ink vehicle may be added to one or more layers of the opticalsecurity device, or it may be used to prepare one or more coatings orseparate layers that are applied or added to the device. In the aboveembodiment, the ink vehicle is either mixed in with a composition usedto form a pigmented or obscuring layer on the print or object layer, oris used to make a coating or separate layer that is applied or added tothe pigmented or obscuring layer.

When the ink vehicle is mixed in with a composition used to from apigmented or obscuring layer, the pigmented sealing or obscuring layercan be formed using one or more of a variety of opacifying coatings orinks, which include both solvent and solvent-free coatings or inks (bothcuring and non-curing). In an exemplary embodiment, the sealing orobscuring layer is formed using a pigmented coating comprising apigment, such as titanium dioxide, dispersed within a binder or carrierof curable polymeric material. Preferably, the sealing or obscuringlayer is formed using radiation curable polymers and has a thicknessranging from about 0.5 to about 5 microns.

When used to make a coating or separate layer that is applied or addedto the pigmented or obscuring layer, the ink or ink vehicle may be usedalone or added to an existing formulation.

In one embodiment, the Mr-signature includes at least two Mr-signals inthe invisible spectral range. Here the at least one of the Mr-signal isin the visible and/or uv-spectral range and at least one Mr-signal is inthe IR-spectral range. Alternatively, the Mr-signal is in the visibleand/or IR-spectral range and at least one Mr-signal is in theUV-spectral range. In a further embodiment, the Mr-signature includes aleast one Mr-signal in the near IR-spectral range (NIR).

In one embodiment, the IR-absorber imparts an Mr-signature that includesa first absorption at a first wavelength and a second absorption at asecond wavelength where the first absorption is lower than the secondabsorption and the first wavelength is lower than lower than the secondwavelength. As such, the slope of the Mr-signature over this wavelengthrange is a negative slope thereby giving the OSD a characteristicsignature readily identifiable and detectable by a signature detector.In a preferred embodiment, this Mr-signature is displayed as a positiveslope if the MrOSD is missing, tampered with or is otherwise notauthentic.

The invention also provides a secured product comprising the MrOSD,wherein the MrOSD is coupled to a substrate of a high security product.As noted, a high security product includes high value articles and highvalue documents. The MrOSD may be embedded within the substrate orlayered over the surface of the substrate and thereby affixed by asuitable adhesive element. Examples of suitable adhesive elementsinclude pressure, heat or water activated adhesives. Naturally, otheradhesive elements will be apparent in view of the present disclosure.

In a preferred embodiment of the secured product, an OSD is at leastpartially embedded within a paper banknote and the IR-component ispresent in an amount ranging from about 0.5 gsm to about 5 gsm; morepreferably from about 2 gsm to about 3.5 gsm. Applicant has found thatsurprisingly the emission from the IR-absorbing component is mostreliably detectable when within these ranges. Alternatively, where theOSD is embedded in a polymeric security document, such as a polymericbanknote, the IR-absorbing component coupled to the OSD is present in anamount ranging from about 0.5 gsm to about 5 gsm, preferably, from about2 gsm to about 3.5 gsm in order to enable detection. Suitable infrareddetectors for detecting infrared rays in the near-, middle- andfar-infrared wavelength ranges include: an LED or incandescent IRemitter in combination with a line scanner, CCD camera, photodiode orother similar detection device.

The invention also provides a use for the MrOSD to secure high securityproducts. As such the MrOSD when coupled to a high security product, isable to thwart counterfeit attempts by being able to authenticate thehigh security product or aestheticize the high security product. Forexample, the MrOSD provides a predetermined characteristic Mr-signatureto the high security product such that a missing or tampered OSD will beindicated by a recognizable difference in the Mr-signature that isdistinguishable from the predetermined characteristic Mr-signature.

The invention also provides a method of making the MrOSD. In oneembodiment, this method comprises (i) forming an OSD which at leastcomprises (a) a focusing layer of focusing elements, and (b) an imagelayer of image elements disposed relative to the focusing layer suchthat a synthetic image is projected by the OSD when the image elementsare viewed through the focusing elements; and optionally (c) at leastone additional layer; and (ii) introducing at least one Mr-component tothe OSD. The Mr-component is as described herein. Likewise theMr-component is coupled to the OSD as described herein.

When the inventive optical security device is used in paper (e.g., paperbanknotes or documents), or applied to a surface of the paper, in orderto be detectable (i.e., reliably measureable) the signal intensity orthe height of the absorption/transmission peaks generated by theIR-reactive pigment is preferably greater than about 10 percent (%)(more preferably, greater than about 25%) of the noise level or signalintensity of the surrounding paper.

When the inventive optical security device is used in polymer sheetmaterials (e.g., polymer banknotes or documents), or applied to asurface of the polymer sheet material, in order to be detectable (i.e.,reliably measureable) the signal intensity or height of theabsorption/transmission peaks generated by the IR-reactive pigment ispreferably greater than about 50% (more preferably, greater than about75%) of the noise level or signal intensity of the surrounding polymersheet material.

It is noted that while the IR or UV absorbance (or transmittance) ofthese Mr-components may be detectable from the isolated optical securitydevice, once the device is placed, for example, on or partially within apaper sheet material, the effect becomes scattered or weak, which mayrender the effect undetectable or not reliably measurable. In anexemplary embodiment of the present invention, the polymer(s) used tomake the inventive optical security device is 100% transmissive, and theoptical security device is present on or partially within a paper sheetmaterial having a basis weight ranging from about 70 to about 110 gramsper square meter (g/m2 or gsm). In this exemplary embodiment, thecharacteristic IR-signature of the inventive MrOSD is reliablymeasureable in that the device absorbs or reflects more than 75 percent(%) of any near IR light when viewed in transmission (% T<25% from750-950 nanometers (nm)).

In one exemplary embodiment, the IR-absorbing component is detectable inonly the infrared region of the electromagnetic spectrum and is presentin the form of a binary code. Two means for authentication are offeredby way of this embodiment of the inventive optical security device,namely, the characteristic IR signature and the IR binary code.

In another exemplary embodiment, the IR-absorbing component isdetectable in both the infrared and the visible regions of theelectromagnetic spectrum and is present in the form of a binary code.Four means for authentication are offered by this embodiment, namely,the characteristic IR signature, the IR binary code, the visibleappearance, and the visible binary code.

The UV-absorbing component used in the subject invention may beobservable in only the ultraviolet region of the electromagneticspectrum or it may be observable in both the ultraviolet and the visibleregions of the electromagnetic spectrum. Similar to the IR-absorbingcomponent, the UV-absorbing component may be present in a continuousmanner or in the form of an intermittent pattern.

In one exemplary embodiment, the UV-absorbing component is observable inonly the ultraviolet region of the electromagnetic spectrum and ispresent in the form of a binary code. Two means for authentication areoffered by the inventive optical security device of this embodiment,namely, the characteristic UV signature and the UV binary code.

In another exemplary embodiment, the UV-absorbing component isobservable in both the ultraviolet and the visible regions of theelectromagnetic spectrum and is present in the form of a binary code.Four means for authentication are offered by this embodiment, namely,the characteristic UV signature, the UV binary code, the visibleappearance, and the visible binary code.

In yet another exemplary embodiment, a combination of IR-absorbing andUV-absorbing components are present in the MrOSD. One or both of thesecomponents may also be observable in the visible region and may bepresent in either a continuous or intermittent pattern.

The MrOSD may be used in the form of, for example, a security strip,thread, patch, or overlay and mounted to a surface of, or partiallyembedded within a fibrous or non-fibrous (e.g., polymer) sheet material(e.g., banknote, passport, ID card, credit card, label), or commercialproduct (e.g., optical disks, CDs, DVDs, packages of medical drugs),etc., for authentication purposes. The inventive device may also be usedin the form of a standalone product (e.g., substrate for subsequentprinting or personalization), or in the form of a non-fibrous sheetmaterial for use in making, for example, banknotes, passports, and thelike, or it may adopt a thicker, more robust form for use as, forexample, a base platform for an ID card, high value or other securitydocument.

When used in the form of a security strip, thread, patch, or overlay,the total thickness of the inventive device is preferably less thanabout 50 microns (more preferably, less than about 45 microns, and mostpreferably, from about 10 to about 40 microns).

The security strips, threads, patches and overlays may be partiallyembedded within or mounted on a surface of a document. For partiallyembedded strips and threads, portions thereof are exposed at the surfaceof the document at spaced intervals along the length of the strip orthread at windows or apertures in the document.

The inventive optical security devices may be at least partiallyincorporated in security papers during manufacture by techniquescommonly employed in the papermaking industry. For example, theinventive security device in the form of a strip or thread may be fedinto a cylinder mould papermaking machine, cylinder vat machine, orsimilar machine of known type, resulting in partial embedment of thestrip or thread within the body of the finished paper.

The security strips, threads, patches and overlays may also be adheredor bonded to a surface of a document with or without the use of anadhesive. Bonding without the use of an adhesive may be achieved using,for example, thermal welding techniques such as ultrasonic welding,vibration welding, and laser fusing. Adhesives for adhering theinventive devices to a surface of a document may be one of hot meltadhesives, heat activatable adhesives, water-activated adhesives,pressure sensitive adhesives, and polymeric laminating films. Theseadhesives are preferably crosslinkable in nature, such as UV curedacrylic or epoxy, with crosslinking achieved while the adhesive is inthe melt phase.

Suitable documents into which the MrOSD may be integrated or otherwiseembedded include those of any kind having financial value, such asbanknotes or currency, bonds, checks, traveler's checks, lotterytickets, postage stamps, stock certificates, title deeds and the like,or identity documents, such as passports, ID cards, driving licenses andthe like, or non-secure documents, such as labels. The MrOSD is alsocontemplated for use with consumer goods as well as bags or packagingused with consumer goods.

In another contemplated embodiment, the inventive device forms part of alabel construction. The inventive device may be placed on the inside ofa package, so that the synthetic image(s) remains visible.

When used in the form of a base platform for an ID card, high value orother security document, the total thickness of the inventive device ispreferably less than or equal to about 1 millimeter (mm) including (butnot limited to) thicknesses: ranging from about 200 to about 500microns; ranging from about 50 to about 199 microns; and of less thanabout 50 microns.

While various embodiments of the present invention have been describedabove, it should be understood that they have been presented by way ofexample only, and not limitation. Thus, the breadth and scope of thepresent invention should not be limited by any of the exemplaryembodiments.

The invention will be further clarified by reference to certain specificdrawings reflecting certain specific embodiments of the presentinvention.

The Mr-component may be present in a continuous manner or in the form ofan intermittent pattern. As best shown in FIG. 1 , the intermittentpattern may be in the form of similar or different size horizontal bars(see FIGS. 1 a, 1 d, 1 e ), chevrons or zig zags (see FIG. 1 c ), angledbars (see FIG. 1B), shapes, indicia (see FIG. 1 f ), or the like, orcombinations thereof.

In one embodiment, as illustrated in FIG. 2 , the Mr-component (210) ofthe MrOSD (200) is a patterned layer integrated into the image layer(205), where the MrOSD comprises a focusing layer of focusing elements(201) disposed over the image layer (205) of image elements (202) andsurrounding solid regions (203). A spacer layer (204) is disposedbetween the focusing elements (201) and the image elements (202). Herethe image elements are voids partially filled with a contrastingelement.

In a further exemplary embodiment, as depicted in FIG. 3 , theMr-component (310) of the MrOSD (300) is a discrete layer disposedbetween an image layer (305) of image elements (302) and an opacifyinglayer (306). The MrOSD (300) comprises a spacer layer (304) disposedbetween a focusing layer of focusing elements (301) and an image layer(305) of image elements (302) (filled voids) and surrounding solidregions (303).

In another exemplary embodiment, as depicted in FIG. 4 , theMr-component (410) of the MrOSD (400) is integrated with the MrOSD as apatterned layer disposed between the MrOSD's spacer layer (404) andimage layer. Here the image elements (402) are protrusions (402), whichmay be printed onto the spacer layer (404). Here the MrOSD comprises aspacer (404), which is disposed between a focusing layer of focusingelements (401) and an array of image elements (402). The MrOSD (400)also includes an additional layer (406) which functions as an adhesivelayer.

In another exemplary embodiment, as depicted in FIG. 5 , the MrOSD (500)is as described in FIG. 4 . The MrOSD (500) comprises a spacer layer(504), which is disposed between a focusing layer of focusing elements(501) and an array of image elements (502). Here the Mr-component (510)is integrated into the OSD by being distributed in an additional layer(506).

The MrOSD, in one embodiment, is illustrated by FIG. 6 , wherein theimage elements (602) of MrOSD (600) are dollar signs arranged in anarray in the image layer beneath the spacer layer (604). The spacerlayer (604) is disposed between the image elements (602) and thefocusing layer of focusing elements (601). Here, the Mr-component (610)is a discrete layer of an IR-absorber having very little absorption inthe visible spectral range, but is detectable in the IR spectral rangesuch that at least two Mr-signals are detectable in the invisiblespectral range.

A secured product prepared using the MrOSD of FIG. 6 (marked withreference number (712)) is exemplified in FIG. 7 . Here, the syntheticimage (720) of MrOSD (600) projected by the image elements, when viewedthrough the focusing elements (601) of FIG. 6 , is a dollar sign. TheMrOSD (600) is coupled to a substrate (711) of the high security product(700). The high security product (700) is a banknote having the MrOSD(712) coupled to the banknote substrate as a partially embedded (e.g.,windowed) thread, where the thread weaves in and out of the paper.

Presence of an authentic MrOSD can be confirmed by a signature detector.An authentic MrOSD will indicate a predetermined characteristicMr-signature. An exemplary predetermined characteristic Mr-signature(800) is depicted by FIG. 8 , wherein the top curve indicates a thread,such as an OSD without an Mr-component, while the bottom curve indicatesa thread, such as an OSD with the Mr-component shown by the presence ofthe characteristic Mr-signature. As noted in the spectrograph of FIG. 8, the slope of the Mr-signals in the wavelength range of from 800 to 900nm increases when the Mr-component is missing and decreases when theMr-component is present as you increase the wavelength.

It should be understood that the Mr-component may alternatively beintegrated into multiple layers of the OSD. Moreover, it is alsocontemplated herein that the focusing elements are reflective or acombination of refractive and reflective. Alternative predeterminedMr-signatures are also contemplated, including specific absorption oremission at specific wavelengths.

What is claimed is:
 1. A machine-readable optical security device(MrOSD) comprising: a spacer layer comprising a first side and a secondside; a layer of focusing elements disposed on the first side of thespacer layer; an array of image elements disposed on the second side ofthe spacer layer; an additional layer disposed on the second side of thespacer layer, wherein the additional layer covers the array of imageelements; and a machine-readable component (Mr-component) distributedwithin the additional layer, wherein the Mr-component is not visible ina visible in a visible spectral range when viewed through the layer offocusing elements and the spacer layer, and wherein the MrOSD furthercomprises an image layer and the array of image elements is disposedrelative to the layer of focusing elements such that a synthetic imageis projected by the MrOSD when image elements of the array of imageelements are viewed through focusing elements of the layer of focusingelements.
 2. The MrOSD of claim 1, wherein the Mr-component is a firstinfrared (IR) component imparting a machine readable signature(Mr-signature) which includes a machine readable signal (Mr-signal)within an IR spectral range.
 3. The MrOSD of claim 2, wherein theMr-component provides at least two Mr-signals within an invisiblespectral range.
 4. The MrOSD of claim 1, wherein the Mr-componentprovides an Mr-signal in a near infrared spectral range.
 5. The MrOSD ofclaim 1, wherein the Mr-component imparts an Mr-signature that includesa first absorption at a first wavelength and a second absorption at asecond wavelength where the first absorption is lower than the secondabsorption and the first wavelength is lower than the second wavelength.6. The MrOSD of claim 1, wherein image elements of the array of imageelements comprise a material contrasting with the spacer layer.
 7. TheMrOSD of claim 1, wherein the Mr-component is a first ultraviolet (UV)component imparting an Mr-signature which includes an Mr-signal within aUV spectral range.
 8. The MrOSD of claim 1, wherein the Mr-componentcomprises an IR taggant which absorbs infrared light of a firstwavelength and emits light at a second wavelength.
 9. The MrOSD of claim1, wherein the Mr-component comprises a UV taggant which absorbsultraviolet light of a first wavelength and emits light at a secondwavelength.
 10. The MrOSD of claim 1, wherein the MR-component comprisesan IR-taggant selected from a substituted phthalocyanine, anaphthalocyanine, a metal-containing phthalocyanine, or apoly-substituted phthalocyanine.
 11. The MrOSD of claim 1, wherein theMR-component is an IR-taggant comprising a benzenethiol-substitutedcopper-phthalocyanine.
 12. The MrOSD of claim 1, wherein theMr-component is integrated with the spacer layer by being embedded inthe spacer layer.
 13. The MrOSD of claim 1, wherein the Mr-componentprovides at least two signals within a UV spectral range.
 14. The MrOSDof claim 1, wherein the Mr-component provides at least two signalswithin an IR spectral range.